# Contagion dynamics of extremist propaganda in social networks

## TL;DR

This paper analyzes how ISIS extremist propaganda spreads on social media, revealing that influential supporters act like infectious agents in an epidemic, which can inform countermeasures against online extremism.

## Contribution

It introduces a novel computational approach using dynamical activity-connectivity maps to quantify the influence and contagion of extremist content on social networks.

## Key findings

- ISIS supporters generate highly-infectious information cascades.
- Radical propaganda spreads similarly to epidemics.
- Influential users significantly amplify content dissemination.

## Abstract

Recent terrorist attacks carried out on behalf of ISIS on American and European soil by lone wolf attackers or sleeper cells remind us of the importance of understanding the dynamics of radicalization mediated by social media communication channels. In this paper, we shed light on the social media activity of a group of twenty-five thousand users whose association with ISIS online radical propaganda has been manually verified. By using a computational tool known as dynamical activity-connectivity maps, based on network and temporal activity patterns, we investigate the dynamics of social influence within ISIS supporters. We finally quantify the effectiveness of ISIS propaganda by determining the adoption of extremist content in the general population and draw a parallel between radical propaganda and epidemics spreading, highlighting that information broadcasters and influential ISIS supporters generate highly-infectious cascades of information contagion. Our findings will help generate effective countermeasures to combat the group and other forms of online extremism.